Original: 37,671 bytes
ScolorQ: 7,755 bytes
Photoshop: 7,640 bytes
The pictures are hotlinked from scolorq.
And finally my algorithm at 4 colors.
The truth is oddly, that my algorithm is crap for color picking. I'm not very good at it yet. And need a few more things to really make it pop. Here's the SColorQ colors with my positional color dither.
My thing can't even pick colors and it's better. Or at least has some noted advantages.
Slightly different settings for the dilthering.
And yet a different setting... Which is pretty insane in and of itself.
Which turns out to be rather cool as an effect. Cooler when you realize that it salvages a lot of the depth of the gradient and such that was otherwise lost at an expense of becoming insane.
To really mess with your head. Here it is, not even color quantized. I fed it raw CYMK (Cyan, Yellow, Magenta, Black).
Not messed with enough. Here's KCYM. The exact same color except I changed the order. (Yes. The order!)
Keep in mind. This isn't even quantized. This is just rendering the picture in Cyan, Magenta, Yellow and Black.
Getting rid of the order requirement and making it a total free for all, this is *still* 4 colors. And not even quantized. Just CYMK.
Here is RGBWCYMK so all the 8 combinations of solid colors.
And bringing it back full circle, here's ScolorQ's 4 colors with my dither, sans ordering and pareto-optimal.